title: Perfluorocarbons enhance a T2*-based MRI technique for identifying the penumbra in a rat model of acute ischemic stroke.
abstract: Accurate imaging of ischemic penumbra is crucial for improving the management of acute stroke patients. T2* magnetic resonance imaging (MRI) combined with a T2*oxygen challenge (T2*OC) is being developed to detect penumbra based on changes in blood deoxyhemoglobin. Using 100% O2, T2*OC-defined penumbra exhibits ongoing glucose metabolism and tissue recovery on reperfusion. However, potential limitations in translating this technique include a sinus artefact in human scans with delivery of 100% OC and relatively small signal changes. Here we investigate whether an oxygen-carrying perfluorocarbon (PFC) emulsion can enhance the sensitivity of the technique, enabling penumbra detection with lower levels of inspired oxygen. Stroke was induced in male Sprague-Dawley rats (n=17) with ischemic injury and perfusion deficit determined by diffusion and perfusion MRI, respectively. T2* signal change was measured in regions of interest (ROIs) located within ischemic core, T2*OC-defined penumbra and equivalent contralateral areas during 40% O2±prior PFC injection. Region of interest analyses between groups showed that PFC significantly enhanced the T2* response to 40% O2 in T2*-defined penumbra (mean increase of 10.6±2.3% compared to 5.6±1.5% with 40% O2, P<0.001). This enhancement was specific to the penumbra ROI. Perfluorocarbon emulsions therefore enhances the translational potential of the T2*OC technique for identifying penumbra in acute stroke patients.
authors.affiliation: Wellcome Surgical Institute, Glasgow Experimental MRI Centre, Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK.
authors.forename: Graeme A
authors.initials: GA
authors.lastname: Deuchar
authors.forename: David
authors.initials: D
authors.lastname: Brennan
authors.forename: Hugh
authors.initials: H
authors.lastname: Griffiths
authors.forename: I Mhairi
authors.initials: IM
authors.lastname: Macrae
authors.forename: Celestine
authors.initials: C
authors.lastname: Santosh
mesh_terms: D000818:Animals; D001802:Blood Substitutes / Q000494:pharmacology*; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism; D003287:Contrast Media / Q000494:pharmacology*; D004195:Disease Models, Animal; D005466:Fluorocarbons / Q000494:pharmacology*; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D020521:Stroke / Q000000981:diagnostic imaging / Q000378:metabolism
chemical_list: D001802:Blood Substitutes; D003287:Contrast Media; D005466:Fluorocarbons; D006454:Hemoglobins; C100003:deoxyhemoglobin; D010100:Oxygen